HIV stands for Human Immunodeficiency Virus. It is the virus that causes AIDS. A member of a group of viruses called retroviruses, HIV infects human cells and uses the energy and nutrients provided by those cells to grow and reproduce.

AIDS stands for Acquired Immunodeficiency Syndrome. It is a disease in which the body’s immune system breaks down and is unable to fight off infections, known as “opportunistic infections,” and other illnesses that take advantage of a weakened immune system.

When a person is infected with HIV, the virus enters the body and lives and multiplies primarily in the white blood cells. These are immune cells that normally protect us from disease. The hallmark of HIV infection is the progressive loss of a specific type of immune cell called T-helper, or CD4, cells. As the virus grows, it damages or kills these and other cells, weakening the immune system and leaving the person vulnerable to various opportunistic infections and other illnesses ranging from pneumonia to cancer. A person can receive a clinical diagnosis of AIDS, as defined by the U.S. Centers for Disease Control and Prevention (CDC), if he or she has tested positive for HIV and meets one or both of theses conditions:

• The presence of one or more AIDS-related infections or illnesses;
• A CD4 count that has reached or fallen below 200 cells per cubic millimeter of blood. Also called the T-cell count, the CD4 count ranges from 450 to 1200 in healthy individuals.

In some people, the T-cell decline and opportunistic infections that signal AIDS develop soon after infection with HIV. But most people do not develop symptoms for 10 to 12 years, and a few remain symptom-free for much longer. As with most diseases, early medical care can help prolong a person’s life.

A person who has HIV carries the virus in certain body fluids, including blood, semen, vaginal secretions, anal fluids, and breast milk. The virus can be transmitted only if such HIV-infected fluids enter the bloodstream of another person. This kind of direct entry can occur

(1) Through the linings of the vagina, rectum, mouth, and the opening at the tip of the penis;
(2) Through intravenous injection with a syringe; or
(3) Through a break in the skin, such as a cut or sore.

Usually, HIV is transmitted through:

• Unprotected sexual intercourse (either vaginal or anal) with someone who has HIV. Women are at greater risk of HIV infection through vaginal sex than men, although the virus can also be transmitted from women to men. Anal sex (whether male-male or male-female) poses a high risk mainly to the receptive partner, because the lining of the anus and rectum is extremely thin and is filled with small blood vessels that can be easily injured during intercourse.

• Unprotected oral sex with someone who has HIV. There are far fewer cases of HIV transmission attributed to oral sex than to either vaginal or anal intercourse, but oral-genital contact poses a clear risk of HIV infection, particularly when ejaculation occurs in the mouth. This risk goes up when either partner has cuts or sores, such as those caused by sexually transmitted infections (STIs), recent tooth-brushing, or canker sores, which can allow the virus to enter the bloodstream.

• Sharing needles or syringes with someone who is HIV infected. Laboratory studies show that infectious HIV can survive in used syringes for a month or more. That’s why people who inject drugs should never reuse or share syringes, water, or drug preparation equipment. This includes needles or syringes used to inject illegal drugs such as heroin, as well as steroids. Other types of needles, such as those used for body piercing and tattoos, can also carry HIV.

• Infection during pregnancy, childbirth, or breast-feeding (mother-to-infant transmission). Any woman who is pregnant or considering becoming pregnant and thinks she may have been exposed to HIV-even if the exposure occurred years ago-should seek testing and counseling. In the U.S., mother-to-infant transmission has dropped to just a few cases each year because pregnant women are routinely tested for HIV. Those who test positive can get drugs to prevent HIV from being passed on to a fetus or infant, and they are counseled not to breast-feed.

HIV is not an easy virus to pass from one person to another. It is not transmitted through food or air (for instance, by coughing or sneezing). There has never been a case where a person was infected by a household member, relative, co-worker, or friend through casual or everyday contact such as sharing eating utensils or bathroom facilities, or through hugging or kissing. In the United States, screening the blood supply for HIV has virtually eliminated the risk of infection through blood transfusions. Furthermore, you cannot get HIV from giving blood at a blood bank or other established blood collection center. Mosquitoes, fleas, and other insects do not transmit HIV.

If you are sexually active, protect yourself against HIV by practicing safer sex. Whenever you have sex, use a condom or “dental dam” (a square of latex recommended for use during oral-genital and oral-anal sex). When used properly and consistently, condoms are extremely effective. But remember:

• Use only latex condoms (or dental dams). Lambskin products provide little protection against HIV.
•Use only water or silicone based lubricants. Latex condoms are virtually useless when combined with oil- or petroleum-based lubricants such as Vaseline® or hand lotion. (People with latex allergies can use polyethylene condoms with oil-based lubricants).
• Use protection each and every time you have sex.
• If necessary, consult a nurse, doctor, or health educator for guidance on the proper use of latex barriers.

The male condom is the only widely available barrier against sexual transmission of HIV. Female condoms are also effective at preventing HIV and can be purchased at some stores. You can also talk with your doctor about the need and accessibility for PrEP use.

PrEP (Pre-Exposure prophylaxis) is the use of a current HIV medication for the prevention of transmission on HIV before exposure occurs. PrEP is a prescription that can be taken daily and has been found to be effective in the prevention of HIV. This needs to be discussed with your doctor and would need regular follow-up after initiation.

PEP (Post Exposure Prophylaxis) is the use of current HIV medication after a potential exposure. This can be prescribed by a primary care doctor or an Emergency department doctor but must be initialed within 72 hours of the exposure. Follow up with your doctor for more information.

Having a sexually transmitted infection (STI) can increase your risk of acquiring and transmitting HIV. This is true whether you have open sores or breaks in the skin (as with syphilis, herpes, and chancroid) or not (as with chlamydia and gonorrhea). Where there are breaks in the skin, HIV can enter and exit the bloodstream more easily. But even when there are no breaks in the skin, STIs can cause biological changes, such as swelling of tissue, which may make HIV transmission more likely. Studies show that HIV-positive individuals who are infected with another STI are three to five times more likely to contract or transmit the virus through sexual contact.

If you are injecting drugs of any type, including steroids and insulin, do not share syringes or other injection equipment with anyone else. If you are planning to have any part of your body pierced or to get a tattoo, be sure to see a qualified professional who uses sterile equipment.

For many years, there were no effective treatments for HIV/AIDS. Today, a number of drugs are available to treat HIV infection and AIDS. Some of these are designed to treat the opportunistic infections and illnesses that affect people with HIV/AIDS.

In addition, several types of drugs seek to prevent HIV itself from reproducing and destroying the body’s immune system:

• Reverse transcriptase inhibitors attack an HIV enzyme called reverse transcriptase.
• Protease inhibitors attack the HIV enzyme protease.
• Fusion inhibitors stop virus from entering cells.

Many HIV patients take these drugs in combination-a regimen known as active antiretroviral therapy (AART). When taken as directed, anti-HIV treatment can reduce the amount of HIV in the bloodstream to very low levels and sometimes enables the body’s immune cells to rebound to normal levels.

Several drugs can be taken to help prevent a number of opportunistic infections including Pneumocystis carinii pneumonia, toxoplasmosis, cryptococcus and cytomegalovirus infection. Once opportunistic infections occur, the same drugs can be used at higher doses to treat these infections, and chemotherapy drugs are available to treat the cancers that commonly occur in AIDS.

Researchers are continuing to develop new drugs that act at critical steps in the virus’s life cycle. Efforts are under way to identify new targets for anti-HIV medications and to discover ways of restoring the ability of damaged immune systems to defend against HIV and the many illnesses that affect people with HIV. Ultimately, advances in rebuilding the immune systems of HIV patients will benefit people with a number of serious illnesses, including cancer, Alzheimer’s disease, multiple sclerosis, and immune deficiencies associated with aging and premature birth.

There is still no cure for HIV/AIDS.

Despite continued intensive research, experts do not know when we will have a safe, effective, and affordable HIV vaccine. And even after a vaccine is developed, it will take many years before the millions of people at risk of HIV infection worldwide can be immunized. Until then, other HIV prevention methods, such as practicing safer sex and using sterile syringes, will remain critical.

You cannot tell by looking at someone whether he or she is infected with HIV or has AIDS. An infected person can appear completely healthy. But anyone infected with HIV can infect other people, even if they have no symptoms.

Immediately after infection, some people may develop mild, temporary flu-like symptoms or persistently swollen glands. Even if you look and feel healthy, you may be infected. The only way to know your HIV status for sure is to be tested for HIV antibodies-proteins the body produces in an effort to fight off infection. This usually requires a blood sample. If a person’s blood has HIV antibodies, that means the person is infected.

Anyone sexually active or exposed to blood through a needle stick should get an HIV test. Here’s why:
• Even in the early stages of infection, you can take concrete steps to protect your long-term health. Regular check-ups with a doctor who has experience with HIV/AIDS will enable you (and your family members or loved ones) to make the best decisions about whether and when to begin anti-HIV treatment, without waiting until you get sick.

• Taking an active approach to managing HIV may give you many more years of healthy life than you would otherwise have.
• If you are HIV positive, you will be able to take the precautions necessary to protect others from becoming infected.

• If you are HIV positive and pregnant, you can take medications and other precautions to significantly reduce the risk of infecting your infant, including not breast-feeding.